<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="box">
    <h1>aaa</h1>
    <p>pppp</p>
    <span>span</span>
</div>
<script>
    var box = document.getElementById('box');
    console.log(box.children);
</script>
</body>
</html>